[4-10-2012] The U.S. Food and Drug Administration (FDA) has completed its review of recent observational (epidemiologic) studies regarding the risk of blood clots in women taking drospirenone-containing birth control pills. Drospirenone is a synthetic version of the female hormone, progesterone, also referred to as a progestin. Based on this review, FDA has concluded that drospirenone-containing birth control pills may be associated with a higher risk for blood clots than other progestin-containing pills. FDA is adding information about the studies to the labels of drospirenone-containing birth control pills. See Table 1for a list of drospirenone-containing products.

Women should talk to their healthcare professional about their risk for blood clots before deciding which birth control method to use.

Healthcare professionals should consider the risks and benefits of drospirenone-containing birth control pills and a woman’s risk for developing a blood clot before prescribing these drugs.

The studies reviewed did not provide consistent estimates of the comparative risk of blood clots between birth control pills that contain drospirenone and those that do not. The studies also did not account for important patient characteristics (known and unknown) that may influence prescribing and that likely affect the risk of blood clots. For these reasons, it is unclear whether the increased risk seen for blood clots in some of the epidemiologic studies is actually due to drospirenone-containing birth control pills.

The revised drug labels (Beyaz, Safyral, Yasmin and Yaz) will report that some epidemiologic studies reported as high as a three-fold increase in the risk of blood clots for drospirenone-containing products when compared to products containing levonorgestrel or some other progestins, whereas other epidemiological studies found no additional risk of blood clots with drospirenone-containing products. The labels also will include a summary of the previously released results of an FDA-funded study of the blood clot risk.

To put the risk of developing a blood clot from a birth control pill into perspective: The risk of blood clots is higher when using any birth control pills than not using them, but still remains lower than the risk of developing blood clots in pregnancy and in the postpartum period.

Figure 1 shows the risk of developing a blood clot for women who are not pregnant and do not use birth control pills; for women who use birth control pills; for pregnant women; and for women in the postpartum period. For example: If 10,000 women who are not pregnant and do not use birth control pills are followed for one year, between 1 and 5 of these women will develop a blood clot.

Figure 1: Likelihood of Developing a Blood Clot

COC = combination oral contraceptives or birth control pills

These studieswere discussed at the joint meeting of the FDA’s Reproductive Health Drugs Advisory Committee and the Drug Safety and Risk Management Advisory Committee on December 8, 2011. FDA’s briefing document for this meeting is found here.

Previous Drug Safety Communications related to the risk of blood clots with birth control pills that contain drospirenone were posted on May 31, 2011, September 26, 2011, and October 27, 2011. The DSC posted in May 2011 updated the public about FDA’s ongoing safety review of two new studies that reported a greater risk of blood clots for women taking drospirenone-containing products as compared to the risk in women taking products containing other progestins. Previously published studies had reported conflicting findings. The DSC posted in September 2011 discussed preliminary results from a FDA-funded study suggesting an approximately 1.5-fold increase in the risk of blood clots for women who use drospirenone-containing products compared to users of other hormonal contraceptives. The DSC posted in October 2011 released the final study report and appendices from the FDA-funded study in advance of the Joint Meeting of the Drug Safety and Risk Management Advisory Committee and Reproductive Health Drugs Advisory Committee Meeting.

Today's communication is in keeping with FDA's commitment to inform the public about the Agency's ongoing safety review of drugs. FDA will communicate any new information on drospirenone-containing birth control pills and the risk of blood clots when it becomes available.